Antenna system



Sept 5, 1944 R. s. YODER ErAL v 2,357,788

ANTENNA SYSTEM Filed Jan. 25, 1940 3 Sheets-Sheet l Sept. 5, 1944. R s. YoDER Erm.

ANTENNA SYSTEM Filed Jan. 23 1940 3 Sheets-Sheet 2 C, E@ y @S/793g ca//zf/e As' Sept. 5, 1944.

R. s. YoDER ErAL 2,357,788

NTENNI` SYSTEM Filed Jan. 23 1940- 3 Sheets-Sheet 3 Patented Sept. 5, 1944 2,357,788 ANTENNA SYSTEM Raymond S. Yoder and Henry B. Saunders, Chicago, Ill., assignors to Galvin Manufacturing Corporation, Chicago, Ill., -a corporation of Illinois Application January 23, 1 940, Serial No. 315,240

12 Claims This invention relates to antenna systems for radio receiving apparatus and in particular to an adjustable loop antenna for radio receiving apparatus for mobile craft.

In antenna systems for automobiles, it is of the utmost importance that .the system be not only very efcient in its signal pick-up, but also as inconspicuous as possible so as not to impair the appearance of the car. Ordinary antennae of the horizontal and vertical types have been substantially exclusively used in connection with automotive radio receivers, because their elongated form is adapted to installations which are made relatively quickly, and such form does not interfere greatly with the handling of the car. These antennae, however, seldom add to the appearance cf the car and moreover cannot be adjusted relative to 'the direction of radio and interference waves to vary in this manner the ratio of signal energy to noise so as to improve the radio selectivity and reception.

The conventional auto antenna of straight type is not resonant to any frequency in the usual broadcast band and approaches resonance near the band of interfering frequencies. In some instances of travel, therefore, such as in the proximity of street car lines, signs, power lines and the like, the radio signal picked up by these antennae is rendered indiscernible, since the discernibility of the signal depends not only upon the actual strength of the signal energy, but also upon the ratio of the signal energy to that of the intertering noises. This condition is particularlyobjectionable in city travel, because of the heavy distribution of power lines.

Although it is Well known that a directional receiving antenna serves to vary the ratio of signal energy to noise, so as to improve reception, the directional antennae now commercially available are too bulky and unwieldy for satisfactory use in connection with automotive radio receivers.

It is an object of this invention, therefore, to provide an improved loop antenna for radio apparatus for moving craft of all types.

selectivity in the receiver than has heretofore been possible in radio' receivers for automobiles using the ordinary type antennae.

It is a stillfurther object of this invention to provide a loop antenna for an auto radio receiver which Vcan be mounted on the inside of the car in a compact assembly, conveniently located and readily accessible. The outside of the car is thus free of anydefacement, and the antenna is positively protected from exposure to Weather conditions. I

Afurther 'feature of .this invention is the provision of a loop antenna for auto-motive radio receivers, which is remotely located from the receiver but electrically connected with the receiver by av coaxial transmission cable.

Another object of this invention is to provide a loop antenna for auto radio receivers having a conguration that provides for a relatively high pick-.up mass. v

It is a particular ffeature of this invention to provide a loop antenna of narrow width and high pick-up mass and a protectivev housing therefor, which is adaptedv to minimize the interference effects from Wheel and tire static and to substantially reduce theelectro-static noise coupling induced by surrounding interference sources.

It is yet another object of this invention to pro- -x vide a loop antenna for a receiver on a power operated craft which is of rugged construction, of a construction Afor simpleinstallation, and of low cost, and which isfparticularlyV eiective inV reducing thestaticnoises from the motor of the ,tenna and housing therefor being shown in sec- It is a further object of this invention to provide a loop antenna having a narrow Width, so

that the antenna may be of such overall designas to be easily and conveniently located on the outside of an automobile body without impairing .the appearance of the car, nor introducing undesirable Wind resistance.

It is another object of this invention to provide tion and portions of the mounting being in section and broken away. For the purpose of clarity, the antenna and housing are drawn larger than the proportional size in comparison with the car vbody and the coaxial transmission cable is shown in its actual size. l

Fig. 3 is an enlarged sectional view of the an- Ashowing the antenna located inside of the carl body adjacent the dashboard.

Fig. 5 is a sectional view of the housing as seen along line 5--5 in Fig. 4.

Fig. 6 is a further modication of the invention with the antenna located inside of the car and mounted in connection with a rear vision mirror.

Fig. 7 is a fragmentary view showing another arrangement of the antenna and rear vision mirror in the modification of Fig. 6.

Fig. 8 illustrates a further embodiment of the invention with the antenna mounted on the outside of the car body.

Fig. 9 is a sectional view taken on the line 9-9 in Fig. 8.

Fig. 10 is a showing in actual: size ofa loop1 antenna adapted for use with.;` the# mounting. structure in Fig. 1; a portion".Ofi-theantennalv housing being broken away to 'show the construction of the housing and thepositioning of `theantenna loop therein.

Fig. 11 is a fragmentary sectional view through a wall of the antenna housing as seenalong. line II-II in Fig. 1'0, showingthe.electro-staticshield, and a plan View ofthe loop antenna', and

Figs. 12 and 13 are fragmentary sectional views illustrating modified forms of"'an'ele`ctrostatic shield structure for the antenna housing in' Fig. 10.

With referenceV to` the drawings, wherein similar parts areV designated 'by similar numbers throughout the various views, vthereis shown in- Fig. 2, an automobile I" having a radio receiver Il disposed adjacent the. dashboard I2.' The radio receiver is in operative 'associationwitha loop antenna I 3'y which.y is' mountedon the roof ofthe car and is providedfwith anelctro-static shielded housingv I4'. The.antenna.I3 and housing I4 are drawnlfor clarity-.to an enlarged-scale in comparison-to thecar, the actual housingjin onefcommercial embodiment being. only about seven and one-half inches long and threeand one-half inchesin diameter at its widest sections.' and the antenna having a 'width ofA less than three' inches. v

The antenna I3 is of 'substantially spiral'fo'rm with the coil windingsn thereof varranged in the same plane, as is clearlysh'own in Fig. 3. To provide for a high proportion -o'f 4antenna widthv to antenna depth ity is contemplated that the antenna wire of'relativelylow gauge, the antenna width' beingindicated' b'y. the lines A--A` andthe antenna depth bylthe lines B`-B. By virture of thisl constructionthe antenna has a relatively large pick-unmass o'1",' in other Words',Y a relatively high signal'receiving capacity. Also, an antenna of this configuration -is found -to possess a very high Q' resulting. in greater station selectivity-as to adjacent'rchannels of frequencies.

The housing. I4 is preferably formed of`an ap.- propriate phenolic resin or ther like,1 and yincludes mating halves. I6', only one of which .is shown in- Fig. 2,which are provided over'their insidcsurface with a plurality of conductors I1, Vwhich form an electrostatic shield l therein.. Since every conductor provides for. a possible formation ofeddy currents, theconductors I1` are of small cross section. but' off-'fa relatively high ratio ofwidth to depth, and are formed of a high conductingmaterial to effect Vthe greatest advantage in the elimination of'the eddy`- currents. The conductors I1 are arranged'ineach housingV half I6 to emanate from a common"central zone designated as I8 in a directiontoward the edges of such'half.. The zone I8 isals'oshielded with aconductor element whichis connected witha'll of the conductors I1" which" terminate at the edges of the housing half IG. It is thus seen that the combined surface area of the conductors I1 is substantially equal to the total inside surface area of the housing I4. It is to be noted that the connecting Zone I8 is substantially opposite the central portion of the antenna I3, so that the eddy current effects on the antenna are reduced to a minimum. The conductors I1 are raised from the inside surface of the housing walls and are separated from each other by spaces I9, which are formed between adjacent conductors.

The conductors I1 may be formed by placing .a suitable mask over the inside surface of the .housing half I6" and then spraying the mask withlaluminum or copper, which adheres to the unmasked housing surface, the masked surface portions providing for the spaces I9. A shielded housing of this construction, has been found to effect-a very sharp null in the interfering frequencies for alsmall angular directioning of the antenna so as toA maintain a high ratio of signal energy to noise over a broad wave spectrum.

The housing I4r is provided with a baseportion which conforms substantially to the curvature 'of the top of the car I0, a gasket 2I positioned between the housing I4 and the top of the car I0 serving to seal the interior of the housing and hence the antenna from exposure to the weather,

and contamination from dirt, grit and the` like.-

The antenna is suitably mounted to the end 22 of' a coaxial-transmission cable 23', which serves .to'eleotricallyy connect the antenna with the receiv'er I I, in a, manner to be hereinafter fully described. The cable is commercially available and includes substantially cylindrical segments 24, which are adapted toY be extendingly arranged' in a capped formation. Each segment 24 is formedof a dielectric material and is provided centrally thereof with a conductor 26,

which extends therethrough so as to engage' thev conductors 26 in the adjacent segments. A continuous insulated conductor is thus formed by the mating assembly of the segments 24. The segments 24 areA arranged within a shield 21,

which in turn is covered with Va flexible housing.

28'. The cable 23 is thus seen to be both stiff and pliant.

Thecable 23 is rotatably mounted in a sleeveY Y n 29 of conducting characteristics which in turny isv supported in the roof of the car I0 in a manner to be in conducting relation therewith. The sleeve 29 is formedwith an outwardly flanged end 3I` Vwhich is located within the housing I4 and adapted to engage the gasket 2| (Fig, 4). The opposite end of the sleeve 29 is formed with threads for engaging a nut 32, tightening of the nut 32 serving to press toward the car top the spring .member 33` to hold the sleeve 29 in the' car top, in an` obvious. manner'. The nut isformed with an inwardly extending unthreaded annular portion 34, which ts loosely about the cable 23, and serves to position the cable within the sleeve` 29. The cable 23,- nearrthe antenna end 22 has fastened thereto a collar 36, which isV stantially eliminate any jarring action of theantenna during normal operation ofthe automobile.

noted above, it is contemplated that the sleeve 3| be formed of a material having conducting characteristics. Since the sleeve is in conductive relation with the top of the car I0, an unbalanced antenna, having a ground connection of very low impedance is provided by connecting the low potential side of the antenna I3 to the sleeve 29. Static noises picked up by the antenna I3 are thus readily conducted to the ground, whereby to obtain an appreciable reduction in the static which might otherwise be conducted to the receiving apparatus.

The high potential side of the antenna I3 is connected to the lead-in or conductors 26 in the cable segments 24, for transfer of the signal response to the receiver I I, connection of the leadin 26 and the receiver being made through a pin connection 4U which includes a pin 4I and a pin receiving socket 42; the pin 4I being connected with the lead-in 26, and the socket 42 being connected to the condenser 43, by means of the conductor 44. The pin 4I is maintained in the socket portion 42 by threading of the nut 46 about the threads formed on the socket portion. The pin connection is thus seen to provide for a simple relatively movable connection between the cable 23 and radio II to maintain electrical co-ntact therebetween upon rotation of the cable 23. To facilitate rotation of the cable 23 and hence directioning of the antenna, there is provided a knurled knob 41, which is located so as to be readily manipulated by the driver of the car. It is thus seen that the cable 23 serves to electrically connect the antenna I3 with the radio II, to orient the antenna from the radio, and to support the antenna for directioning purposes.

With reference to Fig. 1 the antenna I3 is shown in circuit with a portion of a simple radio circuit. The high potential side of the antenna is fed to the grid of a first R. F. amplifier or modulator 48, through conducto-rs or lead-in 26 and a capacitive coupling or xed isolating condenser 49. The variable condenser 43 is connected across the antenna circuit, and the low potential side of the antenna is grounded to the sleeve 29 through conductor 5I. There is thus provided a resonant circuit for the antenna I3, the loop serving as an antenna or inductance coil, and resonance with each frequency being obtained by the tuning of the condenser 43. As noted above, the particular configuration of antenna I3, with the transverse diameter very much greater than the cross-sectional width, as shown in Fig. 2, provides for a greater pick-up mass and hence for a greater effective height than is obtainable with a vertical antenna. This increase in pick-up mass and the resonant characteristics of the antenna circuit lprovide for an increase in the signal pick-up and hence in the ratio of signal energy to noise.

A modied form of antenna I3 and housing I4 adapted for use with the radio circuit of Fig. 1 and the structure of Fig. 2, is shown in Fig, 10. The antenna 52 is of spider construction and of substantially oval configuration; the spider frame 50 being relatively narrow to provide for a high ratio of antenna width to depth. The

housing I4' is composed of similar halves I6 and is of a form similar to that of the housing I4. Each housing half I6 is provided over its inside surface with conductors I1', spaces I9', and a connecting zone (not shown), which are similar to the conductors II, spaces I9, and zone I8, respectively, hereinabove described in connection with Fig. 2. The outside surface of each half I6' is provided with conductors 53,

which are similar to conductors I'I, but are staggered relative thereto, to provide a solid shield, projectively, about the antenna 52, as is clearly shown in Fig. 10. Since the conductors Y, I'I' and 53 are in a projected overlapped relation it is readily apparent that the projected area of all of the conductors Il' and 53 completely covers the surface area of the housing I4. The conductors 53 are separated from each other by spaces 54, and are arranged to emanate from a common central zone 56 in a direction toward the edges of the housing half. The zone 56 is shielded with a conductor element which is connected with all of the conductors 53, the connecting zone for the conductors Il and the zone 56 being arranged substantially opposite each other for electrical connection by a rivet 5l or the like. Since the connecting zones for the conductors Il' and 53 are also substantially opposite the central :portion of the antenna 52, it is seen that the effect of the eddy currents on the signal response of the antenna is reduced to a minimum. There is thus provided an an# tenna 52 of high pick-upmass and a housing therefor, having a shield, which is solid, projectively, about the antenna for all operating positions of the antenna.

Modiiied forms of shielding structures, which may be used in the housings I4 and I4 are illustrated in Figs. 12 and 13. `With reference to Fig. 12 the shield is molded within the housing wall 59 and is formed from a single flat piece of copper or like material, the lflat conductors 6I being extruded and angled, asrshown, vbut; conf nected to a common conductor 62.r It is to be noted that the angle of the conductors 6I provides for a projected area of the conductors which is substantially equal to the surface area of the housing'. In Fig. 13 the shield is comprised of wire rods 64, which are arranged substantially radially in the housingrwall, the inner` ends of the wires 64 being in common connection at a central zone (not shown) similar to the zones I8 and 56, which were described above; the rods being positioned in close relative proximity to provide a projected area which is substantially equal to the surface area of the housing.

A modified form of the invention is shown in Fig. 4. The loop antenna 66 is composed of two spirally wound coils 6l, which are connected in series and arranged within a spherically shaped housing 68. The antenna 66 and housing 68 are located within the body of the car I0 adjacent the windshield (not shown), but independent thereof, whereby to provide for an eflicient signal pick-up. The antenna 66 and the housing 68 are both relatively small and may be mounted on or adjacent the dashboard I2 without impairing in any way the vision of the driver of the car. The housing 68 is rotatably mounted in the dashboard I2 by a suitable mounting means designated generally as 69. The Ahousing includes a tubular extensionk II in the flat bottom-portion I2 thereof which is adapted to extend through` and be rotated in the' mounting blocks 13 and 14, the portion I2 being supported in rotative engagement on block vT3.V The blocks 'I3 and I4 are located on opposite sides of the dashboard I2 and are secured together by screws 16. The lead-in wire 'I'I is positionedv substantiallyY centrally of the extension 'II, `by annular spacers 'i8 which are formed of a suitable dielectric material; the extension serving' as a shield for the lead-in 11. The' extension 'II is fastened'to the pin of the pin connection 40, the lead-in'II be# ing'connected by' the Spin assembly 48 and conductor 44 to the condenser 2v43,` in the manner hereinabove describedV with reference to Fig; 2,. It is to be noted that the extension 1|, spacers 18 and lead-in 11 provide for acoaxial transmissi'o'n cable betweenfthe antenna 66 and the receiver I I, the cable being rotatable with the housing 68.- The antenna -is' mounted -for rotation with the housing by connection ofthe high and low sides thereof, -to the lead-in 11V and extension 1I, respectively,v the extension serving to ground the antenna-to the frame 'of the car I8. A directioning of the antenna is thus readily obtained'bya suitable turning vof the housing 68.

The housing 68 isr formed of two mating halves 19, Which are secured-together as -by screws 8|. The housing 68 is prvided'with an electro-static shield of a structure shown in Fig. 5. Each housing half 19 has formed over its inner surface conductors 83, which extend radially from a common zone 84 to the outer edges of such half. The

Aconductors 83r are separated from each other by spaces 86;'and are connected at the common zone 84 Which, in the housing assembly, is located substantially intermediate the spiral coils 61, so as to reduce to 'a minimum the effects yof eddy currents on the antenna 66. The conductors 83, zone 84 and spaces' 86'are'formed in a manner similar to the conductors I1, zone I8 and spaces I9, respectively,k which Were described in connection with Fig. 2,.

A-further modified form" of the invention is shown in Fig.` 6 in which an antenna I3 is mounted; in a housing 8,1 whichl is adapted for assembly with a rear'vision mirror 88. The mirror 88 and housin g"81 assembly is provided with a ball portion for a ball and. socket connection with,l a bracket 89, mounted adjacent the Windshield 18, but independent thereof. Thehousing 81 is ofsubstantially flatcircular form and includes an electro-static shield (not shown) of a iorrrnv and structure substantially similar to that described and shownin'Fig." 5. The antenna I3 is connected with the'radio receiverA II by the coaxial transmissionv cable'23 which is-suitably mounted in vtheframeof the car I8. The lead- Y in 26 is connected tothel tuning condenser 43 in the receiver circuit bythe pin connection 48 and conductor 44 which were hereinabove described. The opposite en'd'ofthe'lead-in or conductor 26 is electrically connected'to the high potential side of the antenna I3 through a suitablev ball con# nection 9|: the 10W potential side of the antenna being grounded to the shield 21 through ba11 eennection 92. It is toY be noted that thehousing 81, antenna I3 and mirror 88 are all movable as a unit, relative to the cable 23; the pin connectio'n 40 serving primarily'as arrv assembly expedient. A y

With reference to Fig. .'7 there is shown aV modied Varrangement of the antenna system in Fig. 6.

The bracket 9'3 is mounted adjacent the Wind-V shield 18, butindependent thereof, and is formed with a pair of extending iingers 94. Each finger 94 is provided with a socket'. portion for a ball and socket connection with a mirror 96 and antenna housing 91, respectively; the housing 91 and antenna I3 being located adjacent the mirror 96, but independent ofv the Windshield 18. The mirror 96 and housing 91 are suitably arranged to provide for maximum adjustability of the mirror 96 and the antenna I3; the housing being disposed sov that full vision can be Obtained through the rear viewl mirror. It is'thus seen that the 'mirror 96l and antenna I3 are relatively movable -forl independent adjustment and' thati the housing 91 is so located as to permit full vision of the driver in both the mirror 96 and through the windshield 10.

It is to be understood that in the embodiments of the invention disclosed in Figs, 2, 4, 6 and 7, a proper directioning of the loop antenna is 0btained by a turning movement of about fifteen degrees, so that a proper directional setting is easily accomplished. In the embodiment of Fig.. 6, therefore, the assembly of the antenna I3 with the rear vision mirror 88 does not materially impair the intended utility of the mirror. f

Yet another form of the invention is illustrated in Fig, 8. The antenna (not shown) is mounted within the housing 98 so as to be rotatable therewith, the housing being provided with a hollow extension 99 having a mounting portion |8| thereon adapted to engage the end of a tube |82. The tube |82 which is formed of brass or like material, is rotatably mounted in the top of the car` I8, the lower end of the tube being provided with a ball joint |83 for reception in a-socket portion |84 arranged on the dashboard I2 of the car I8. The antenna lead-in wire |86 from the antenna passes through the extension 99 and tube |82 for electrical engagement with the ball portion |83.V

As shown in Fig. 9 the lead-in wire |86 is arranged substantially centrally of the tube |82 by annular spacers |81 which are formed of a suitable-dielectric material. It is thus seen that a coaxial transmission cable is provided for connecting theantenna with the radio receiver (not shown), the receiver being in electrical connection with the Ysocket portion |84.

It is to be noted that the loW potential side of the antenna may be eiectively grounded by the tube |82 and car VIIl by means of a connecting conductor (not shown) arranged in the extension 99. Directioning of the antenna is obtained by turningof the knob |88, the amount' of turning and hence/'a particular directional settingrof the antenna being determined from a suitable indicator |89. It is to be noted that the housing 98 is of a Vconngurationsimulating that of a spot light so that a turning of the` housing for directioning of the antenna, does not in any manner detract from the appearance of the car.

It is thus seen that the present invention provides for a shielded loop antenna for radio re-` ceivers on mobile craft, which is very small, com? pact and rugged of design and which provides for a high Q, and a highrratio of signal energyto noise over a broad Wave spectrum. The small di-Y mensions of the antenna provide for the locationv of the antenna either in the inside or on the outside of a car bodywithout in any manner impairlustrated in Figs. 2, 5, 10, 12 and 13 may be used in Vconnection with the antenna housings shown in Figs. 2, 4,6, 1 and 8. The circuit diagram in Fig. l, although described speciiically in connec-` tion with the embodiment in Fig. 2, also represents a radio circuit for the antenna systems shown in Figs. 4, 6, 'I and 8.

It is to bev understood further that only preferred embodiments of the present invention have been illustrated and described herein and that further modifications and alterations thereof may be made within the full intended scope of the invention as defined by the appended claims.

We claim:

1. In an antenna system for a mobile craft radio receiving system with said craft having a low impedance ground circuit, an unbalanced loop antenna having the low potential side thereof connected into the low impedance ground circuit of said craft, said antenna being of a width less than three inches and formed of low gauge Wire wound in a substantially spiral form and providing a relatively high pick-up mass, a housing for said antenna, said housing being formed of insulating material and having therein an electro-static shield including conductors which are distributed substantially over the complete surface area of said housing, said conductors being connected at a common zone which is located adjacent an antenna portion of low signal pick-up to reduce to a minimum the effect of eddy currents on said antenna, and means for directively rotating said antenna, said antenna and housing serving to effect a sharp null in the field of interference frequencies to maintain a high ratio of signal energy to noise over a broad wave spectrum.

2. In an antenna system for a mobile craft radio receiving apparatus, a loop antenna of substantially spiral configuration with the windings thereof in the same plane and formed of a low gauge Wire to obtain a high proportion of antenna width to antenna depth, a housing for said antenna, said housing being formed of insulating material and having therein an electro-static shield including conductors having a projected area which substantially covers the complete surface area of said housing said conductors being connected at a common Zone which is disposed substantially opposite the central portion of said antenna to reduce to a minimum the effect of eddy currents on said antenna,

and means for directively rotating said antenna,-

said antenna and electro-static shield serving to effect a sharp null in the interference frequencies, to maintain a high ratio of signal energy to noise over a broad wave spectrum.

3. In antenna apparatus for automotive radio receiving apparatus, a loop antenna including a lead-in wire for electrical connection with said receiving apparatus, said antenna being located outside of said automobile body, a stream-lined housing for said antenna, a tubular support for said housing extending to the radio receiving' apparatus and being substantially straight over its entire length, said tubular support being adapted to receive the said lead-in wire therein to provide a coaxial transmission cable between said antenna and radio receiving apparatus, and means for rotatably mounting said tubular support in the automobile body, said tubular support and the car body serving as a ground circuit for the W potential side of said antenna.

4. In antenna apparatus for a mobile craft radio receiver including a loop antenna, an insulating housing for said antenna formed with a pair of mating portions, an electro-static shield in said housing including conductors of relatively smal cross-section but having a high ratio of width to depth, distributed over substantially the complete inside surface of each of said housing portions, said conductors being directed from a central zone on the inside surface of each housing portion to the edges thereof, said zone being provided with a conductor common to all of said rst conductors.

5. In an antenna system for automotive radio receiving apparatus, having an antenna mounted on the outside of the car body and a radio receiver mounted within the car body adjacent the dashboard, a coaxial transmission cable substantially straight over its entire length for electrically connecting the antenna with said radio receiver, said antenna being of substantially spiral form with the windings thereof in the same plane, a-housing for` said antenna formed of mating halves `and Vhaving an electro-static shield therein including Yconductors having a projected area lsubstantially equal to the surface area of said housing, the conductors in each housing half being connected together at a common zone, said zones being 'substantially oppositely disposed adjacent the central portion of said antenna, said antenna being supported on said coaxial cable, and means for rotatably mounting said coaxial cable in said car body.

6. In antenna apparatus for a mobile craft radio receiver, a'loop antenna located remotely from said receiver, a coaxial transmission cable for electrically connecting said antenna with said receiver, a housing for said antenna formed with mating halves and having an electro-static shield built therein, each vof said housing halves being provided with conductors which substantially cover the inner surface thereof, said conductors being connected at a central common zone and extending radially therefrom to the edges of such housing half, said coaxial cable extending within said housing and having said antenna supported thereon, means for rotatably mounting said coaxial cable in the mobile craft, and a pin connection for rotatably connecting said coaxial cable with said receiver.

7. In antenna. apparatus for automotive radio. receiving apparatus, a loop antenna having a lead-in line for electrical connection with the receiving apparatus, said antenna being located outside of said automobile body, a stream-lined housing for said antenna having an electro-static shield therein, the projected area of said shield substantially covering the surface area of said housing, a tubular support for said housing eX- tending to the radio receiving apparatus and being substantially straight over its entire length, said tubular support being adapted to receive the said lead-in line therein to provide a coaxial transmission cable between said antenna and radio receiving apparatus, and means for rotatably mounting said tubular support in the automobile body including a ball and socket connection which forms a part of the antenna leadin line.

8. In antenna apparatus for a mobile craft radio receiver including -a loop antenna having a portion of low signal pick-up, an insulating housing for said antenna, an electro-static shield in said housing including spaced conductors having a projected area which covers completely the surface area of said housing, said conductors being in electrical connection with a common portion which is located opposite said antenna portion of low signal pick-up, to reduce to a minimum the effects of eddy currents on said antenna.

9. In antenna apparatus for a mobile craft radio receiver including an antenna, an insulating housing for said antenna, an electro-static shield for said antenna including metallic painted portions on saidhousing having a projected area which covers completely the surface area of said housing, sai d portionsk b eing` arranged on opposite sides of the houslnglwall in alprojected overlapping relation and being connected together at pointsA adjacent antenna portions of rlow signal pick-,upi-t yreduceftoa minimum the effectsA of eddy currents onV said antennal` (10.,Innantenna,apparatus for a mobile craft radio receiver, a loop antenna Vof narrow Width and of Asul: stav,r'iti ally, o val lconguratiori, a Ytwo part insulated housing for saiclantenna, an electro-static shield Ain said housingincluding conductrs forix'ied on opposite sideslof said housing Wall in a'projectd'ovcrlapping relation, to provide 'a shield having aQpojcted area which completelfyzcvefr's the `slf'ace of. said housing, allv of the. conductors 'ori'ach loi said'hous'ing parts ,being conn cted together at a common zone; 'said Izones bein? Sflib'StantiallyY oppositely disposed and located adjacent the central portion of said loop.

11. In an antenna system for the radio receiver of a mobile craft, said craft havingk body lmeans, and said radi-0 receiver beine muted within said body means, a loop antenna Having portion of metalliccoated sections and positioned opposite Said antenna portion of 10W signal pick-up, a coaxial transmission cable of substantially straight form electrically connecting said radio receiver with said antenna, and means supporting said coaxial cable within said body means.

12. In an antenna system for a mobile craft radio receiving system having an input circuit, said craft having a low impedance ground circuit, a loop antenna with a portion of 10W signal pick-up, said antenna having the low potential side thereof connected with the low impedance ground circuit of. said craft and the high potential side thereof connected with said input circuit,

low signal pick-up, a housing" for said antenna supported on said body means, lsaid housing being composed of an insulating material and including an electro-static shield having metallic lcoated sections, conductor means common to said a housing for said antenna formed of insulating material, and including an electro-static shield having metallic portions arranged substantially over the complete surface area of said housing, said metallic portions being electrically connected together at a portion of said housing which is located opposite said antenna portion of low signal pick-up to reduce to a minimum the effect of eddy currents on said antenna, said antenna and housing serving to effect a sharp null in the rg5 eld of interference frequencies to maintain a high ratio of signal energy to noise over a broad wave spectrum. Y

' RAYMOND Si. YODER.

HENRY B. SAUNDERS. 

